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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Estudo do impacto dos modelos de propagação no desempenho de protocolos ad hoc em um ambiente VANET urbano / Study of propagation models and ad hoc protocols in an urban environment of VANETs

Galván, William Felix Angeles 06 May 2016 (has links)
CAPES / Diferentes estudos avaliaram o desempenho de protocolos de roteamento Ad hoc para redes veiculares. No entanto, a maioria deles não são realistas pois utilizam modelos de propagação simples para redes veiculares sobre ambiente urbano, o que limita a precisão dos resultados. O objetivo deste trabalho é comparar o impacto no desempenho dos protocolos de roteamento Ad hoc (entre eles AODV, DSR, DYMO e OLSR) em diferentes modelos de propagação (entre eles Espaço Livre, Dois Raios, Nakagami e Sombreamento Log Normal) com valores de parâmetros reais em um mapa urbano real. Os cenários e parâmetros das simulações foram desenvolvidos nos simuladores Omnet++ e SUMO. As métricas avaliadas foram atraso médio fim-a-fim e a taxa de entrega de pacotes. Os resultados mostraram que o comportamento dos protocolos varia bastante conforme o modelo utilizado (modelos simples ou complexos). A contribuição deste trabalho diz respeito à configuração e avaliação de um cenário veicular real em um ambiente urbano, para ser base de estudos futuros e permitir que eles conheçam a resposta desses protocolos de roteamento em diferentes modelos de propagação. / Different studies evaluated the performance of Ad hoc routing protocols for vehicular networks. However, most of them are not realistic because on propagation models are used simple propagation models for vehicular networks on urban environment, which limits the accuracy of the results. The objective of this study is to compare the performance impact of Ad hoc routing protocols (including AODV, DSR, DYMO and OLSR) under different propagation models (including Free Space, Two Ray Ground, Nakagami and Log Normal Shadowing) with real parameters values in an existing urban map. The scenarios and parameters of the simulations were developed in Omnet++ and SUMO simulators. The evaluation metrics were the average end-to-end delay and the package delivery rate. The results showed that the behavior of protocols varies widely depending on the model used (complex or simple model). The contribution of this work concerns the configuration and evaluation of a real vehicular scenario in an urban environment, to be the basis of future studies to allow them know the response of these routing protocols in different propagation models.
52

Estudo do impacto dos modelos de propagação no desempenho de protocolos ad hoc em um ambiente VANET urbano / Study of propagation models and ad hoc protocols in an urban environment of VANETs

Galván, William Felix Angeles 06 May 2016 (has links)
CAPES / Diferentes estudos avaliaram o desempenho de protocolos de roteamento Ad hoc para redes veiculares. No entanto, a maioria deles não são realistas pois utilizam modelos de propagação simples para redes veiculares sobre ambiente urbano, o que limita a precisão dos resultados. O objetivo deste trabalho é comparar o impacto no desempenho dos protocolos de roteamento Ad hoc (entre eles AODV, DSR, DYMO e OLSR) em diferentes modelos de propagação (entre eles Espaço Livre, Dois Raios, Nakagami e Sombreamento Log Normal) com valores de parâmetros reais em um mapa urbano real. Os cenários e parâmetros das simulações foram desenvolvidos nos simuladores Omnet++ e SUMO. As métricas avaliadas foram atraso médio fim-a-fim e a taxa de entrega de pacotes. Os resultados mostraram que o comportamento dos protocolos varia bastante conforme o modelo utilizado (modelos simples ou complexos). A contribuição deste trabalho diz respeito à configuração e avaliação de um cenário veicular real em um ambiente urbano, para ser base de estudos futuros e permitir que eles conheçam a resposta desses protocolos de roteamento em diferentes modelos de propagação. / Different studies evaluated the performance of Ad hoc routing protocols for vehicular networks. However, most of them are not realistic because on propagation models are used simple propagation models for vehicular networks on urban environment, which limits the accuracy of the results. The objective of this study is to compare the performance impact of Ad hoc routing protocols (including AODV, DSR, DYMO and OLSR) under different propagation models (including Free Space, Two Ray Ground, Nakagami and Log Normal Shadowing) with real parameters values in an existing urban map. The scenarios and parameters of the simulations were developed in Omnet++ and SUMO simulators. The evaluation metrics were the average end-to-end delay and the package delivery rate. The results showed that the behavior of protocols varies widely depending on the model used (complex or simple model). The contribution of this work concerns the configuration and evaluation of a real vehicular scenario in an urban environment, to be the basis of future studies to allow them know the response of these routing protocols in different propagation models.
53

Přestavba křižovatky Pisárecká – Veslařská v Brně / Reconstruction of crossing Pisárecká - Veslařská, Brno

Tejkal, David January 2015 (has links)
The main reason of doing this master thesis is reconstruction crossroad Pisarecka – Veslarska in Brno with growing traffic intensity up every year. Obviously had to be observed the best safety draw around the walking and bicycle area. This crossroad is using like transfer place. The result of this work is to elaborate of the situation including charasteristic cut sections and longitudinal profile of main road. Part of this work is an estimate of the financial cost to realize this building.
54

HPV pro městský provoz a seniory / Citybike

Černý, Pavel January 2011 (has links)
Content of this diploma thesis is a construction design of human powered vehicle for city ride with a focus on seniors. It deals with the issue of bicycle in city traffic and rates construction modern citybikes with a view to their weaknesses for the purpose. The basis of this work is a design frame with custom geometry, which is fitted commonly available components. Using FEM analysis are revealed critic areas of construction and results are used to optimize the frame.
55

Management of City Traffic, Using Wireless Sensor Networks with Dynamic Model

Rahman, Mustazibur 16 April 2014 (has links)
Road network of a region is of a paramount importance in the overall development. Management of road traffic is a key factor for the city authority and reducing the road traffic congestion is a significant challenge in this perspective. In this thesis, a Wireless Sensor Network (WSN) based road-traffic monitoring scheme with dynamic mathematical traffic model is presented that will not necessarily include all adjacent intersections of a block; rather the important major intersections of a city. The objective of this scheme is to reduce the congestion by re-routing the vehicles to better performing road-segments by informing the down-stream drivers through broadcasting the congestion information in a dedicated radio channel. The dynamic model can provide with the instantaneous status of the traffic of the road-network. The scheme is a WSN based multi-hop relay network with hierarchical architecture and composed of ordinary nodes, Cluster-Head nodes, Base Stations, Gateway nodes and Monitoring and Control Centers (MCC) etc. Through collecting the traffic information, MCC will check the congestion status and in defining the congestion, threshold factors have been used in this model. For the congested situation of a road-segment, a cost function has been defined as a performance indicator and estimated using the weight factors (importance) of these selected intersections. This thesis considered a traffic network with twelve major intersections of a city with four major directions. Traffic arrivals in these intersections are assumed to follow Poisson distribution. Model was simulated in Matlab with traffic generated through Poisson Random Number Generator and cost function was estimated for the congestion status of the road-segments over a simulation period of 1440 minutes starting from midnight. For optimization purpose we adopted two different approaches; in the first approach, performance of the scheme was evaluated for all threshold factor values iteratively one at a time, applying a threshold factor value to define threshold capacities of all the road segments; traffic was generated and relative cost has been estimated following the model specifications with the purpose of congestion avoidance. In the second approach, different values of threshold factor have been used for different road segments for determining the optimum set-up, and exhaustive search technique has been applied with a smaller configuration in order to keep computations reachable. Simulation results show the capacity of this scheme to improve the traffic performance by reducing the congestion level with low congestion costs.
56

Management of City Traffic, Using Wireless Sensor Networks with Dynamic Model

Rahman, Mustazibur January 2014 (has links)
Road network of a region is of a paramount importance in the overall development. Management of road traffic is a key factor for the city authority and reducing the road traffic congestion is a significant challenge in this perspective. In this thesis, a Wireless Sensor Network (WSN) based road-traffic monitoring scheme with dynamic mathematical traffic model is presented that will not necessarily include all adjacent intersections of a block; rather the important major intersections of a city. The objective of this scheme is to reduce the congestion by re-routing the vehicles to better performing road-segments by informing the down-stream drivers through broadcasting the congestion information in a dedicated radio channel. The dynamic model can provide with the instantaneous status of the traffic of the road-network. The scheme is a WSN based multi-hop relay network with hierarchical architecture and composed of ordinary nodes, Cluster-Head nodes, Base Stations, Gateway nodes and Monitoring and Control Centers (MCC) etc. Through collecting the traffic information, MCC will check the congestion status and in defining the congestion, threshold factors have been used in this model. For the congested situation of a road-segment, a cost function has been defined as a performance indicator and estimated using the weight factors (importance) of these selected intersections. This thesis considered a traffic network with twelve major intersections of a city with four major directions. Traffic arrivals in these intersections are assumed to follow Poisson distribution. Model was simulated in Matlab with traffic generated through Poisson Random Number Generator and cost function was estimated for the congestion status of the road-segments over a simulation period of 1440 minutes starting from midnight. For optimization purpose we adopted two different approaches; in the first approach, performance of the scheme was evaluated for all threshold factor values iteratively one at a time, applying a threshold factor value to define threshold capacities of all the road segments; traffic was generated and relative cost has been estimated following the model specifications with the purpose of congestion avoidance. In the second approach, different values of threshold factor have been used for different road segments for determining the optimum set-up, and exhaustive search technique has been applied with a smaller configuration in order to keep computations reachable. Simulation results show the capacity of this scheme to improve the traffic performance by reducing the congestion level with low congestion costs.
57

Traffic-related Pollution: Implications for Environmental Justice and Policy

Shearston, Jenni A. January 2023 (has links)
Traffic is a problem across the globe, reaching perniciously into cities and communities nearly everywhere. The United States (US) has its share of traffic problems; of the ten cities with the highest traffic delay times in 2022, four were in the US. While nearly everyone living in the US has likely experienced traffic congestion of some kind, some cities are notoriously worse than others. In New York City (NYC), traffic congestion has been a problem as far back as 1913, when Fifth Avenue was so traffic-clogged it could take 40 minutes to go 23 blocks. Today, of the 25 most congested traffic corridors in the US, three are in NYC. One of these runs through the South Bronx, an environmental justice neighborhood we highlight in this dissertation. Traffic congestion is a source of air pollution (traffic-related air pollution, or TRAP) and noise, and it can result in property damage, injuries, and fatalities from collisions with other vehicles, pedestrians, or those using other forms of transportation. Both traffic congestion and TRAP have been associated with numerous negative health outcomes. For example, TRAP is associated with respiratory, cardiovascular, neurological, and pregnancy outcomes, including asthma exacerbation, incident childhood and adult asthma, reduced lung function, atherosclerosis, hypertension, stroke, myocardial infarction, cardiovascular-related mortality, cognitive decline, neurodevelopmental outcomes, pregnancy loss, term low birth weight, and small for gestational age birth. In general across the US, communities of color and higher-poverty neighborhoods face greater exposure and health burden from traffic. Throughout this dissertation, we study traffic congestion and TRAP through two lenses: (1) environmental justice; and (2) policy. Additionally, we assess the cardiovascular health impacts of TRAP. In Chapter 1, we provide background on the problem of traffic, focusing on NYC and the South Bronx. In Chapter 2, we present a case study from the South Bronx, where a new trucking-intensive warehouse was opened in 2018. In this study, we quantified the increase in vehicles and trucks following the opening of the warehouse and estimated the resulting increases in black carbon (BC) and noise. We discuss the injustice in the methods used to assess the environmental impact of the warehouse, the warehouse’s siting in a predominantly Black and Lantinx community already overburdened with trucking-intensive industries, and the desire of the community to instead use the land for a community park. In Chapter 3, we present a study quantifying how traffic congestion in NYC changed during the COVID-19 pandemic. We assess how NY on Pause, the state’s stay-at-home order, impacted traffic congestion by comparing the magnitude of traffic decreases in environmentally burdened or systematically disadvantaged neighborhoods to the magnitude of decreases in less burdened and more advantaged neighborhoods. We discuss the implications of these results for upcoming traffic policies in NYC, such as congestion pricing. In Chapter 4, we present a study evaluating diurnal changes in TRAP in NYC during NY on Pause. We discuss the implications of these results for congestion pricing, including the potential timing of TRAP decreases. In Chapter 5, we present an epidemiologic study of TRAP and myocardial infarction (MI) in New York State, identifying hazard windows of exposure in a study period where the mean nitrogen dioxide (NO₂) concentration was substantially lower than the hourly national standard. We discuss implications for the NO₂ National Ambient Air Quality Standards (NAAQS) and suggest that the current standard may be insufficient to protect population cardiovascular health. Finally, in Chapter 6, we conclude with a discussion of recommended research directions and policy considerations.
58

Access and constraints to commuting in Gauteng Province, South Africa

Chakwizira, James 05 1900 (has links)
PhD (Environmental Sciences) / Department of Urban and Regional Planning / See the attached abstract below

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